patho exam 3

Overview

  • This section focuses on the liver, its functions, diseases, and related pathology such as infection, inflammation, and cirrhosis.

  • Topics covered will appear on exam three.

Anatomy and Physiology of the Liver

  • Location:

    • Positioned in the right upper quadrant of the abdomen, beneath the diaphragm.

  • Weight:

    • Approximately 1,500 grams in adults.

  • Protection and Structure:

    • Encased with Gleason's capsule, made of thick connective tissue.

    • Organized into lobules.

  • Blood Supply:

    • Dual blood supply comprising:

    • Hepatic Artery: Supplies 25% of blood, a branch of the aorta.

    • Portal Vein: Drains venous blood from the gastrointestinal (GI) tract and supplies 75% of blood.

    • Portal Triad: Contains branches of the artery, venous blood vessels, and bile duct.

  • Liver Cell Types:

    • Hepatocytes: Functional liver cells responsible for several metabolic processes.

    • Kupffer Cells: Specialized macrophages that detoxify harmful substances; described as the "cleanup crew."

    • Sinusoids: Vascular spaces between hepatocytes containing a mixed blood supply.

Functions of the Liver

  • General Functions:

    • Digestion:

    • Manufactures bile, critical for digestion, secreted into the hepatic duct and common bile duct.

    • Bilirubin Conjugation:

    • Converts bilirubin into its water-soluble form with glucuronic acid.

    • Fat Metabolism:

    • Transforms triglycerides into fatty acids, cholesterol, and glycerol. Supports energy production.

    • Protein Metabolism:

    • Synthesizes and breaks down proteins. Produces most of the body's albumin; deamination converts proteins into ammonia, excreted in urine.

    • Carbohydrate Metabolism:

    • Stores glucose as glycogen. Processes glycogenolysis (breakdown of glycogen) and gluconeogenesis (creation of glucose).

  • Hematological Functions:

    • Produces coagulation factors using vitamin K.

  • Endocrine Role:

    • Pancreatic glucagon stimulates lipolysis and manages glycogen breakdown.

  • Detoxification:

    • Biotransformation occurs, changing substances for excretion, influenced by the first-pass effect.

  • Storage:

    • Stores vitamins (A, D, B12), iron, copper, and produces B lymphocytes.

Liver Dysfunction

  • Cholestasis:

    • Condition where bile flow is obstructed, causing a blockage similar to a traffic jam.

  • Hepatocellular Injury:

    • Inflammation damages liver cells, disrupting detoxification, leading to accumulation of drugs and metabolites.

  • Common Causes of Liver Dysfunction:

    • Viral infections (e.g., hepatitis), drugs, toxic environmental substances, excessive alcohol consumption.

Hepatitis Family

  • General information on Hepatitis:

    • Systemic liver infection primarily caused by viruses:

    • Hepatitis A: RNA virus, fecal-oral route, commonly through contaminated food/water.

    • Hepatitis B: DNA virus, transmitted via blood/body fluids; risk for liver cancer; has specific markers (s, c, e).

    • Hepatitis C: RNA virus, blood transmission, can remain dormant until symptomatic.

    • Hepatitis D: Depends on HBV to infect, accelerates damage.

    • Hepatitis E: Similar to Hepatitis A, associated with contaminated water in developing countries.

  • Clinical Symptoms & Examination:

    • Jaundice is a significant symptom, characterized by yellowing of the skin and eyes, first visible in the sclera. This stems from hyperbilirubinemia (elevated bilirubin levels in blood).

    • Causes of Jaundice:

    1. Prehepatic: Excessive breakdown of red blood cells causing bilirubin overload.

    2. Intrahepatic: Hepatocellular injury impeding conjugation.

    3. Posthepatic: Obstruction of bile duct preventing bilirubin excretion (e.g., gallstones, tumors).

  • Chronic Hepatitis:

    • Lasting longer than six months, leading to continuing liver inflammation.

Hepatitis Overview

  • Hepatitis A (HAV):

    • Contaminated food/water (fecal-oral route); incubation period 14-21 days; prevention via vaccination and hygiene practice.

  • Hepatitis B (HBV):

    • Blood and bodily fluid transmission; can lead to cancer; four stages with a vaccine available.

  • Hepatitis C (HCV):

    • RNA virus, blood transmission, can remain asymptomatic for years.

  • Hepatitis D (HDV):

    • Dependency on HBV for replication; worsens liver disease.

  • Hepatitis E (HEV):

    • Fecal-oral route similar to HAV; predominant in developing countries, often related to water sanitation.

Treatment and Preventive Measures

  • Educate patients about the risks of medications like Tylenol, the importance of adhering to dosing instructions, and potential liver damage.

  • Promote lifestyle modifications such as weight loss, healthy diets, diabetes management, and increased physical activity for those with nonalcoholic fatty liver disease.

  • Highlight the potential dangers of mixing alcohol with medications, particularly with hepatotoxic drugs.